turndownPronunciation: /ˈtəːndaʊn/Definition of turndown noun 1a rejection or refusal: no idea should meet a flat turndown if there’s a chance of a pay-off 2a decline in something; a downturn: the company has suffered a dramatic turndown after a storm of bad publicity adjective (of a collar) turned down. turndown in other Oxford dictionaries Definition of turndown in the US English dictionary